This application is based on application No.2000-181653 filed in Japan, the contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a non-magnetic mono-component developing device in an image-forming apparatus, such as a copying machine and a printer, and to a toner for such a device.
2. Description of the Related Art
Conventionally, with respect to a developing device used for an image-forming apparatus such as a copying machine and a printer, a two-component developing system using a two-component developing agent containing toner and carrier and a mono-component developing system using a mono-component developing agent containing only toner have been known. Of these two developing systems, it has been known that the mono-component developing system is more suitable in order to meet recent demands for compact image-forming apparatuses. In particular, in the case of color image-forming apparatuses having a plurality of developing devices for housing toners of a plurality of colors, it is more essential to make developing devices more compact.
In a color image-forming apparatus having developing devices of the mono-component developing system, in each of the developing devices, in general, toner charged by a regulating member is transported by a toner-supporting member to a developing area facing an electrostatic latent image-supporting member, and after an electrostatic latent image on the electrostatic latent image-supporting member is developed by the toner to form a toner image, these toner images are superposed with or without using an intermediate transfer member, and transferred on a sheet of recording paper and fixed thereon. In order to make such a color image-forming apparatus more compact, it is sometimes necessary to move the electrostatic latent image-supporting member upward from below at the developing area.
In the case when the electrostatic latent image-supporting member is moved upwards from below at the developing area, from the viewpoint of high image quality, in the developing device, it is necessary to provide an arrangement in which: the toner-supporting member is moved upward from below at the developing area, a toner-supplying member for supplying toner to the toner-supporting member and the toner-supporting member are made to rotate in the same direction, and at a portion where the toner-supplying member and the toner-supporting member come into contact with each other, the toner-supplying member and the toner-supporting member are allowed to move in opposite directions from each other (see U.S. Pat. No. 5,797,075 and Japanese Patent Application Laid-Open No. Hei 10-171226(1998)).
However, when a known toner is applied to the above-mentioned image-forming apparatus, a comparatively great stress is imposed on the toner particles, resulting in a problem of degradation in the toner fluidity. The degradation in the fluidity causes less amount of toner to be transported to the developing area by the toner-supporting member, or unevenness in the thickness of the toner layer formed on the toner-supporting member; and the resulting problems are a reduction in the density in the copy image and deterioration in the gradation of the copy image, and, in particular, in the case of a solid image, unevenness in density and cloud tends to occur.
The present invention is to solve above problems of the mono-component developing device in an image-forming apparatus.
Such a problem is solved by using a mono-component developing toner having a weight-average particle size of from 4 to 10 xcexcm, a compression rate of not more than 32% and an angle of repose of not more than 38xc2x0.